Deep-fried graphene could revolutionise battery tech

The pom-poms of graphene were created using a process similar to deep-frying

Chemistry of Materials

Deep-fried pom-poms of graphene could make batteries smaller and more efficient. The super-material, which is just one atom thick, has been turned into three-dimensional structures by spraying graphene oxide droplets into a hot solvent.

The new technique provides a simple means of using graphene to make electrode materials for batteries. Graphene is the most conductive material known to man, but its physical properties require it to be altered for use in batteries.

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As graphene is very thin and flat its surface area is limited -- this is key as the surface area of an electrode has a huge impact on battery power.

Experiments to make 3D blobs of graphene have had mixed results, but now material scientists at Yonsei University in Seoul, South Korea have claimed a breakthrough. The team used a process likened to deep-frying to create graphene nanospheres and microspheres that are ideally suited for use as electrodes. The findings were published in the journal <a style="background-color: transparent;" href="http://pubs.acs.org/doi/abs/10.1021/cm5034244">Chemistry of Materials</a>.

Using an ultrasonic nozzle the researchers created microdroplets of graphene oxide, which were dropped into a 160C mixture of organic solvent and reducing agent. This turned the graphene oxide into graphene, evaporated the water and created the deep-fried pom-poms of graphene.

The appearance of the graphene is a result of how it forms in the solvent. Tiny nanosheets of graphene radiate out from the centre of the ball, increasing the exposed surface area and improving charge transfer. Early tests with the graphene pom-poms showed that they performed better as electrodes compared to standard sheets of graphene.

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The same technique was also used to combine graphene with silicon, further enhancing its potential for use in batteries of the future.

In the future this and other applications of graphene could be used to make technology smaller, faster and more efficient. The material was first discovered at the University of Manchester in 2003, which will soon be the site of the National Graphene Institute, a new £61m research centre due for completion later this year.

The creators of graphene were awarded a Nobel Prize in 2010. At the time of the award the Nobel committee speculated on what graphene was capable of. They explained that a hammock measuring 1sqm would be able to support 4kg -- about the same weight as a well-fed cat. The hammock itself would weigh 0.77mg, or the same as one of the cat's whiskers.